Izharul Haq

Evaluation of bioremediation potentiality of ligninolytic Serratia liquefaciens for detoxification of pulp and paper mill effluent

Due to high pollution load and colour contributing substances, pulp and paper mill effluents cause serious aquatic and soil pollution. A lignin-degrading bacterial strain capable of decolourising Azure-B dye was identified as lignin peroxidase (LiP) producing strain LD-5. The strain was isolated from pulp and paper mill effluent contaminated site. Biochemical and 16S rDNA gene sequence analysis suggested that strain LD-5 belonged to the Serratia liquefaciens. The strain LD-5 effectively reduced pollution parameters (colour 72%, lignin 58%, COD 85% and phenol 95%) of real effluent after 144h of treatment at 30°C, pH 7.6 and 120rpm. Extracellular LiP produced by S. liquefaciens during effluent decolourisation was purified to homogeneity using ammonium sulfate (AMS) precipitation and DEAE cellulose column chromatography. The molecular weight of the purified lignin peroxidase was estimated to be ∼28kDa. Optimum pH and temperature for purified lignin peroxidase activity were determined as pH 6.0 and 40°C, respectively. Detoxified effluent was evaluated for residual toxicity by alkaline single cell (comet) gel electrophoresis (SCGE) assay using Saccharomyces cerevisiae MTCC 36 as model organism. The toxicity reduction to treated effluent was 49.4%. These findings suggest significant potential of S. liquefaciens for bioremediation of pulp and paper mill effluent.

Assessing hazardous risks of indoor airborne polycyclic aromatic hydrocarbons in the kitchen and its association with lung functions and urinary PAH metabolites in kitchen workers.

BACKGROUND Indoor air pollution is associated with decreased pulmonary function but the relative impact of pollution from kitchen sources on health risks in kitchen workers is not well-known or studied. A study was conducted to measure the kitchen indoor air quality including PAHs estimation and risk assessment based on reported PAHs in indoor air in a central kitchen at North India. METHODS A cross sectional study was undertaken to assess the lung function status using spirometer and urinary PAH metabolite measurements using GC-MS/MS among 94 male kitchen workers and their corresponding controls. Assessment of the indoor air quality levels was evaluated using standard methods. RESULTS All the indoor air pollutants were within the recommended guidelines except CO, TVOC and PAH emission in the kitchen. Incremental life time cancer risk (ICLR) based on indoor air PAH measurements indicates potential for carcinogenic risk. Significant lung function decline was observed among kitchen workers as compared to controls after adjusting for smoking habits. Urinary PAH metabolites were detected in kitchen workers and measured concentrations were comparatively higher than control subjects. CONCLUSION The decline in lung functions after adjustment for confounders and detection of urinary PAH metabolites in kitchen workers can be associated with higher concentrations of PAHs, CO and TVOCs in kitchen indoor air.

Improved enzyme properties upon glutaraldehyde cross-linking of alginate entrapped xylanase from Bacillus licheniformis

Enzyme immobilization is an exciting alternative to improve the stability of enzymatic processes and economic viability in terms of reusability. In the current study, purified xylanase from B. licheniformis Alk-1 was immobilized within glutaraldehyde activated calcium alginate beads and characterized in respect of free enzyme. Immobilization increases the optimum pH and temperature of entrapped and cross-linked enzyme from pH=8.0 to 9.0 and 50-60°C. The kinetics parameter of immobilized (cross-linked) enzyme showed an increase in Km (from 4.36mg/mL to 5.38mg/mL) and decrease in Vmax (from 383 IU/mg/min to 370 IU/mg/min). Immobilization increases the optimum reaction time for xylan degradation of immobilized xylanase from 15 to 30min when compare to free form. The storage stability study suggested that the immobilized enzyme retains 80% of its original activity at 4°C after 30days compared to free enzyme (5%). Further, immobilization improved enzyme stability in presence of different additives. The immobilized (cross-linked) enzyme also exhibited adequate recycling efficiency up to five reaction cycles with 37% retention activity. The finding of this study suggests improvement of overall performance of immobilized xylanase in respect to free form and can be used to make a bioreactor for various applications such as poultry feed preparations.

Detection of Tannery Effluents Induced DNA Damage in Mung Bean by Use of Random Amplified Polymorphic DNA Markers

Common effluent treatment plant (CETP) is employed for treatment of tannery effluent. However, the performance of CETP for reducing the genotoxic substances from the raw effluent is not known. In this study, phytotoxic and genotoxic effects of tannery effluents were investigated in mung bean (Vigna radiata (L.) Wilczek). For this purpose, untreated and treated tannery effluents were collected from CETP Unnao (UP), India. Seeds of mung bean were grown in soil irrigated with various concentrations of tannery effluents (0, 25, 50, 75, and 100%) for 15 days. Inhibition of seed germination was 90% by 25% untreated effluent and 75% treated effluent, compared to the control. Plant growth was inhibited by 51% and 41% when irrigated with untreated and treated effluents at 25% concentration. RAPD technique was used to evaluate the genotoxic effect of tannery effluents (untreated and treated) irrigation on the mung bean. The RAPD profiles obtained showed that both untreated and treated were having genotoxic effects on mung bean plants. This was discernible with appearance/disappearance of bands in the treatments compared with control plants. A total of 87 RAPD bands were obtained using eight primers and 42 (48%) of these showed polymorphism. Irrigating plants with untreated effluent caused 12 new bands to appear and 18 to disappear. Treated effluent caused 8 new bands and the loss of 15 bands. The genetic distances shown on the dendrogram revealed that control plants and those irrigated with treated effluent were clustered in one group (joined at distance of 0.28), whereas those irrigated with untreated effluent were separated in another cluster at larger distance (joined at distance of 0.42). This indicates that treated effluent is less genotoxic than the untreated. Neis genetic similarity indices calculated between the treatments and the control plants showed that the control and the plants irrigated with treated tannery effluent had a similarity index of 0.75, the control and plants irrigated with untreated 0.65, and between the treatments 0.68. We conclude that both untreated and treated effluents contain genotoxic substances that caused DNA damage to mung beans. CETP Unnao removes some, but not all, genotoxic substances from tannery effluent. Consequently, use of both untreated and treated wastewater for irrigation poses health hazard to human and the environment.

Evaluation of the Phytotoxic and Genotoxic Potential of Pulp and Paper Mill Effluent Using Vigna radiata and Allium cepa

Pulp and paper mill effluent induced phytotoxicity and genotoxicity in mung bean (Vigna radiata L.) and root tip cells of onion (Allium cepa L.) were investigated. Physicochemical characteristics such as electrical conductivity (EC), biological oxygen demand (BOD5), chemical oxygen demand (COD), and total phenols of the pulp and paper mill effluent were beyond the permissible limit specified for the discharge of effluent in inland water bodies. Compared to control plants, seedling exposed to 100% effluent concentration showed a reduction in root and shoot length and biomass by 65%, 67%, and 84%, respectively, after 5 days of treatment. A. cepa root tip cells exposed to effluent concentrations ranging from 25 to 100% v/v showed a significant decrease in mitotic index (MI) from 32 to 11% with respect to control root tip cells (69%) indicating effluent induced cytotoxicity. Further, the effluent induced DNA damage as evidenced by the presence of various chromosomal aberrations like stickiness, chromosome loss, anaphase bridge, c-mitosis, tripolar anaphase, vagrant chromosome, and telophase bridge and micronucleated and binucleated cell in A. cepa. Findings of the present study indicate that pulp and paper mill effluents may act as genotoxic and phytotoxic agents in plant model system.

Endocrine-Disrupting Pollutants in Industrial Wastewater and Their Degradation and Detoxification Approaches

Endocrine-disrupting chemicals (EDCs), a group of chemicals that alter the normal function of the endocrine system of humans and wildlife, are a matter of great concern. These compounds are widely distributed in respective environments such as water, wastewater, sediments, soils, and atmosphere. Chemicals like pesticides, pharmaceuticals and personal care products, flame retardants, natural hormones, heavy metals, and chemicals derived from basic compounds (such as plasticizers and catalysts) are major endocrine disruptors. EDCs emerging from industries such as pulp and paper, tannery, distillery, textile, pharma, etc. have been considered as major source of contamination. Alkylphenol ethoxylates (APEOs), bisphenol A (BPA), phthalates, chlorophenols, norethindrone, triclosan, gonadotropin compounds, pesticides, etc. are generally escaped during wastewater treatment and contaminate the environment. Endocrine-disrupting activity of these compounds is well documented to have adverse effect on human-animal health. Globally, efforts are being approached for their efficient removal from sewage/wastewaters. Thus, this chapter provides updated overview on EDC generation, characteristics, and toxicity as well as removal/degradation techniques including physical, chemical, and biological methods. This chapter also reviews the current knowledge of the potential impacts of EDCs on human health so that the effects can be known and remedies applied for the problem as soon as possible.